Ply Yard
About Gomoku
Gomoku calculation begins with immediate winning threats, then proceeds to open threes, four-stone threats, and combined attacks. Brief rules do not imply shallow strategy. Freestyle gomoku, exact-five gomoku, and renju differ in their treatment of overlines, double-threes, and double-fours.
- Ruleset covered
- Site freestyle rules: 15×15; five or more wins; no automatic renju restrictions
- Updated
- · Editorial policy and corrections
GomokuRules and variant distinctions
Placement on a 15×15 board
Players alternate placing a stone on an empty intersection. Black moves first, and placed stones do not move. The board described here is 15×15. A legal placement must also satisfy any opening procedure in effect; do not assume that every gomoku or renju variant uses an unrestricted opening.
Five in a row and overlines
A winning line is continuous and horizontal, vertical, or diagonal, with no empty intersection or opposing stone interrupting it. This subsite's freestyle rules accept five or more consecutive stones. An overline of six or more is therefore different from an overline under exact-five gomoku or restricted renju rules. Confirm the variant before evaluating a claimed win.
Open threes and four-stone threats
Evaluate a threat by its legal continuations, not by stone count alone. An open three can normally be extended to an open four; an open four has two immediate winning points. A closed four generally has one. Board edges, opposing stones, gaps, and any forbidden-move rules can change which continuations actually exist.
Freestyle gomoku is not renju
Freestyle gomoku does not automatically impose renju's restrictions on Black. Renju regulates double-threes, double-fours, and overlines and may use a prescribed opening procedure to address the first-move advantage. Their definitions require the full rules, including the legality of continuations. Do not adjudicate a freestyle game with renju restrictions merely because the stone pattern looks familiar.
Wins, draws, and forced defense
If a legal placement completes the required line, the game ends in a win. If the available intersections are exhausted with no winning line, the result is a draw. Before developing a longer attack, check whether the opponent can win on the next move. A defensive move must address the actual winning point or points; simply placing a stone near the threat may accomplish nothing.
Practical strategy
Scan every direction for immediate wins
Before placing a stone, inspect horizontal, vertical, and both diagonal lines for each side. Find immediate winning points first, then compare developing moves. Checking only the most visible line can miss a diagonal threat or a winning continuation through a gap.
Identify the continuations that make a threat forcing
For each three- or four-stone formation, list the legal moves that extend it. Distinguish an open four from a four with only one winning point. Consider the board edge and blocked endpoints, and check any renju restrictions only when that ruleset is actually in use.
Build coordinated threats and review the first forced reply
Look for candidate moves that prepare threats along more than one line, but calculate the opponent's immediate wins before assuming a successful combination. During review, identify the first move that forced a defensive response and the preceding move that enabled it. Memorizing the final five-stone line alone does not explain the attack.
A common misconception
Black's double-threes, double-fours, and overlines are prohibited in every gomoku game.
These restrictions belong to particular renju rulesets. The site's freestyle rules allow five or more to win. Confirm forbidden-move and swap-opening settings before play.
Position study: A four with one defensive point
On rank 8, White occupies G8; Black occupies H8, I8, J8, and K8; L8 is empty. White to move. Assume there is no immediate win or stronger forcing threat elsewhere.
| F | G | H | I | J | K | L | M | |
|---|---|---|---|---|---|---|---|---|
| 10 | ||||||||
| 9 | ||||||||
| 8 | × | |||||||
| 7 | ||||||||
| 6 |
Where must White respond, and is Black's four open?
Show the answer and analysis
White must play L8 to prevent Black from completing five on the next move. G8 is occupied by White, so L8 is the only direct winning endpoint. Black's formation is not an open four.
Four stones alone do not fully describe a threat. List the actual winning points, checking blocked endpoints and the board edge. If both ends were open, blocking only one would normally leave the other winning move.
This position was constructed for instruction. It is not a tournament record or an engine-verified proof of an optimal move. Evaluate it under the stated conditions; do not assume unlisted features of the complete position.
Structured practice
Understand the rules
Construct a closed four, an open four, and a four-stone formation containing a gap. List the immediate winning points.
Assessment: Identify one, two, or the gap-dependent winning points by calculation, not stone count alone.
Compare candidate moves
Find a candidate that prepares both horizontal and diagonal threats, then check whether the opponent can win first.
Assessment: Include the opponent's forcing replies. Do not assume the defender must cooperate with your planned attack.
Review and verify
Record the first position in a game requiring a forced defensive response and review the move that created it.
Assessment: Explain which connection point made the threat forcing rather than showing only the final five-stone line.
Frequently asked questions
How do you win a game of gomoku?
Form a continuous horizontal, vertical, or diagonal line of your stones. There may be no empty point or opposing stone within the line. This site's freestyle setting accepts five or more; other variants require exactly five or restrict overlines. Verify the rules before treating a six-stone line as a win.
How does freestyle gomoku differ from renju?
Freestyle gomoku generally has no Black-only forbidden moves. Renju uses restrictions and opening procedures to address the first-move advantage. Double-threes, double-fours, and overlines are among its important categories, but their legality cannot be determined from names or rough shapes alone. Identify the actual ruleset before applying those restrictions.
What are an open three and a closed four?
An open three is a formation that can normally be extended in one move to an open four with two winning endpoints. A closed four generally has one immediate winning point. Check whether endpoints are empty, continuations are legal, and the board edge interferes. Under renju, an apparent extension may also be prohibited.
Can an open four be stopped with one defensive move?
A genuine open four normally has two immediate winning points, so blocking one endpoint leaves the other. Defense usually has to prevent the formation earlier. However, an immediate win for the defending side or a rules-based restriction on an attacking continuation can change the result. Calculate the actual position rather than applying the pattern mechanically.
Is the center always the best opening move?
Central points offer room to extend in several directions, making them a useful starting point for study. That does not establish one universally best move independently of the opening rules. Some variants prescribe early placements or use swap procedures. Follow those requirements, then evaluate spacing and coordination.
What skills does gomoku develop?
Gomoku develops directional scanning, threat recognition, and short-range calculation. Before each move, identify the opponent's immediate winning points and your own forcing continuations. In review, explain the role of each critical intersection rather than memorizing a diagram. That reasoning transfers more readily to unfamiliar positions.
How does a four-three attack differ from VCF?
A four-three attack combines a four-stone threat with an open-three threat. VCF means victory by continuous fours: a forcing sequence of four-stone threats leading to a win. The concepts can interact, but they are not interchangeable. For either, calculate every legal defensive reply and confirm that each claimed threat really forces a response under the selected rules.
What happens if the board fills without a winning line?
The game is a draw if all available intersections are occupied and neither player has completed a qualifying line. A position must still be evaluated under the selected variant's winning conditions. Many practical games end before the board is full, but frequency does not change the rule.
Where must White respond in the example, and is Black's four open?
White must play L8 to prevent Black from completing five on the next move, given the stated absence of stronger threats elsewhere. White at G8 blocks the other end, so L8 is the only direct winning point: this is not an open four. List actual winning continuations instead of identifying a threat solely by counting four stones.
Are double-threes, double-fours, and overlines forbidden in every gomoku game?
No. Those restrictions belong to particular renju rulesets, not to every gomoku variant. The site's freestyle rules page allows a line of five or more to win. Before starting, confirm whether forbidden moves or a swap opening are enabled.
Put your understanding into practice.
Choose one skill to work on in your next game. A clear reason for each move is more useful than an immediate win.
Play GomokuRules sources and editorial notes
- Current rules for this game on Ply Yard
Identifies the board variant and interface described here. Platform instructions are not a complete statement of every tournament ruleset.
- Renju International Federation: What Is Renju?
Explains why renju and freestyle gomoku are different rulesets and why renju restrictions cannot be imported indiscriminately.
This guide combines the relevant board's rules with independently constructed examples and exercises. It distinguishes basic rules, variant-specific provisions, and strategic advice. Rules sections draw on the sources listed above. Instructional positions have not been presented as exhaustively engine-verified or certified by professional players.
Written by Ply Yard. Independent review by a named professional player has not been completed. To report an issue, send the game, ruleset, position, and relevant source provision to contact@plyyard.com.
